Currently, photolithography techniques are used to fabricate most of the fine patterns in electronic circuits of semiconductors, displays, and other electronic products; however, limits exist on manufacturing inexpensive products using photolithography techniques. Moreover, when attempting to manufacture electronic products having increased surface areas, maintaining low manufacturing costs while using fabrication methods employing photolithography techniques has been difficult.
In view of this current situation, application of printing techniques to manufacturing electronic circuits, sensors, and other devices, these being known as “printed electronics,” is under investigation. Such methods are expected to reduce chemical substance usage and have attracted attention as environmentally friendly manufacturing processes. Moreover, such methods have been applied to printing electrodes of membrane keyboards, automotive window glass heating wires, and RFID (Radio Frequency Identification) tag antennas, among others.
In printed electronics, control of base material (printed side) wettability is of critical importance. Control of wettability is achieved by controlling surface free energy, for which various methods have been proposed. Among these, base materials having a surface free energy difference patterning have been proposed.
For example, PLT 1 describes a technique of separated application in which a surface is modified with radiation or generated ozone via a mask to form a pattern of a surface free energy difference to which an ink is coated. However, in the technique described in PLT 1, although a surface free energy difference is formed in the base material, because this surface free energy difference is low, in the case of applying ink to the surface, the technique cannot realize completely separated application but can only accomplish a film thickness difference in a coating film.
Furthermore, PLT 2 describes a technique of exposing a portion of a surface using a transparency difference of a Fresnel lens to form a low surface free energy portion before exposing the unexposed portion while submersed in water to form a high surface free energy portion. Moreover, a technique of coating ink to the formed pattern before peeling away excess ink to form a pattern is described. However, as in PLT 1, the technique described in PLT 2, although forming a surface free energy difference in the base material, cannot realize separated application through simply applying ink to the surface, and requires processes for peeling the ink from a portion (low surface free energy portion) in which ink deposition is not desired.
Furthermore, PLT 3 describes a technique of modifying a portion of a surface with radiation via a mask to form a surface free energy difference pattern before transferring with heat and pressure to form a pattern. However, the technique described in PLT 3, although forming a pattern by transferring a functional ink layer to a surface free energy pattern, requires heat and pressure at the time of application as well as processes for peeling away excess material.
Furthermore, PLT 4 describes a technique of selectively applying a coating composition to a coating film to which a pattern of a surface free energy difference of a master has been transferred. However, in the technique described in PLT 4, forming a pattern by selectively applying a coating composition having a high surface tension such as a water-based conductive coating composition has been difficult.